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IDProjectCategoryView StatusDate SubmittedLast Update
0010924Dwarf FortressDwarf Mode -- Petspublic2018-10-08 07:582018-10-08 08:02
Assigned To 
Platform64 bitOSWindowsOS Version10
Product Version0.44.12 
Target VersionFixed in Version 
Summary0010924: consistent bird breeding is impossible due to laying/hatching timings and mating/sitting exclusion
DescriptionThis combination of mechanics makes it impossible to maintain a consistent egg-layer breeding program (i.e. hatching and raising for meat and leather, not just harvesting eggs):

1) Hens (and all female egg layers) lay eggs every 3 months (~100000 ticks?)
2) Hens must sit on fertile eggs for 3 months for them to hatch
3) Hens cannot mate while sitting on eggs

As a result, every third clutch of eggs will always be infertile, because her 6-month pregnancy will expire while sitting on the second clutch but she will lay and sit on the third clutch *immediately* after the second hatches, leaving her no time to mate again in between.
Steps To Reproduce* Pasture 1 male and 1 female (non-sterile, non-asexual, non-homosexual) egg-laying bird in a room with a nest box.
* Ensure that eggs are not removed (disabled for cooking, disabled in all stockpiles).
* Butcher all hatchlings immediately to avoid pet population caps.
* Watch the hen lay, sit on, and hatch two fertile clutches of eggs followed by an infertile clutch, repeatedly.
Additional InformationEgg-laying pets/livestock appear to have 6-month (200000 tick) pregnancies just like their mammalian counterparts, with the differences that the pregnancy will not end with a live birth, but if a nest box is available they will lay a clutch of eggs every 3 months (100000 ticks?), and that clutch of eggs will be fertile if and only if the hen had an active pregnancy at the time they were laid.

So far so good, but the problem is that sitting on fertile eggs until they hatch also takes a full 3 months, and the hen cannot mate to get pregnant again while sitting on eggs.

As a result it seems impossible to maintain a consistent output of fertile eggs. When a hen gets pregnant, that pregnancy will last 6 months during which she will be able to lay 2 fertile clutches of eggs. But while sitting on the second clutch, the pregnancy will expire and the hen will be unable to mate again while still sitting on those eggs. When they hatch, she will lay the next clutch of eggs immediately, before she has a chance to mate again. Only when these infertile eggs are cleared, allowing the hen to leave the nest box, will she mate again and be ready to lay two more fertile clutches before repeating the cycle.

Changes to any of the three mechanics listed in the description should alleviate the problem. The change that would have the least impact on player experience would be 0000003; if hens could mate while sitting on eggs, simply putting the male and female in a room/pasture with a nest box should consistently produce fertile clutches, just as the player expects.

If mating while sitting presents a technical challenge (not sure how animal "jobs" are tracked), then a simpler solution with only minimal gameplay change would be changing 0000002; if fertile eggs hatched after (say) 2 months instead of 3, that would give the hen plenty of time between clutches in which to mate again, while still only laying a clutch of eggs every 3 months.
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taleden (reporter)
2018-10-08 08:02

Whoops, used '#' to refer to the list in the description but forgot that would be interpreted as links to other bugs, and can't see a way to edit that out now.

- Issue History
Date Modified Username Field Change
2018-10-08 07:58 taleden New Issue
2018-10-08 08:02 taleden Note Added: 0038864

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